Black mould is a toxic fungus that grows in areas with high humidity. Bathrooms are especially susceptible to black mould, which can implant itself within Sheetrock and cause not only unsightly black spots on your walls and ceiling, but headaches, nausea and respiratory distress in you and your family members. Fortunately, there are simple and inexpensive ways to prevent black mould from occurring or reoccurring in your bathroom paint.
Remove paint if currently growing black mould. Put on your rubber gloves and face mask, and wipe down the entire wall surface (not just the stained areas) with full-strength chlorine bleach. Wait at least 12--and preferably 24--hours to allow the bleach to dry and kill the fungus in your walls.
Wash down the bathroom walls, baseboards and cabinets with a weak soap and water solution. Allow to dry for at least 12 hours.
Mask off any areas not to be painted (such as baseboards, cabinets, sinks and tile) with painter's tape. Place a dust sheet on the floor to prevent paint splashes.
Thoroughly mix your mould-resistant primer. Paint around the masked areas with the paintbrush for better control, then cover the rest of the walls using the roller. Ventilate the bathroom and allow to dry for 24 hours. If any old paint is showing through your primer after it dries, give the walls another coat of primer and allow to dry for 24 hours.
Thoroughly mix your mould-resistant topcoat paint. Paint around the masked areas with the paintbrush, and then cover the rest of the walls with the topcoat paint using the roller. Ventilate the bathroom, and allow the paint to dry for 24 hours. If any of the primer shows through the topcoat, give the walls another coat of paint and allow to dry for 24 hours.
If mould reoccurs in your bathroom despite the mould-proof paint, contact a licensed contractor to check for leaks and/or replace the Sheetrock in your bathroom.
Be careful not to load too much paint onto your brush or roller. Too much paint will cause unsightly drip marks on the walls.
When cleaning black mould off your walls, it is extremely important to ventilate the bathroom properly, or you are likely to pass out from the combination of mould and bleach fumes. Open a window if possible, and set up a fan to blow air out of the bathroom into the hallway or adjacent room.